Allow passing of can_stream in openai_models.py (#600)

* Allow passing of can_stream in openai_models.py

Fixes #599 

* Only set can_stream: false if it is false

Refs #600 (comment)

* Docs for can_stream: false

---------

Co-authored-by: Simon Willison <swillison@gmail.com>

docs/other-models.md

@@ -45,6 +45,8 @@ You can set `api_key_name` to the name of a key stored using the {ref}`api-keys`
 
 Add `completion: true` if the model is a completion model that uses a `/completion` as opposed to a `/completion/chat` endpoint.
 
+If a model does not support streaming, add `can_stream: false` to disable the streaming option.
+
 Having configured the model like this, run `llm models` to check that it installed correctly. You can then run prompts against it like so:
 
 ```bash

llm/default_plugins/openai_models.py

@@ -61,6 +61,9 @@ def register_models(register):
         api_version = extra_model.get("api_version")
         api_engine = extra_model.get("api_engine")
         headers = extra_model.get("headers")
+        kwargs = {}
+        if extra_model.get("can_stream") is False:
+            kwargs["can_stream"] = False
         if extra_model.get("completion"):
             klass = Completion
         else:
@@ -73,6 +76,7 @@ def register_models(register):
             api_version=api_version,
             api_engine=api_engine,
             headers=headers,
+            **kwargs,
         )
         if api_base:
             chat_model.needs_key = None